Present surveysynthesized information on fish biodiversity in theperennial freshwater body of Ramnagar, East Midnapore district of West Bengal, India. We documented 45 fish species under 29 genera, 18 families and 8 orders during the periods from1990 to 1995, whereas, 34 species from 21 genera and 12 families under 7 orders were recorded presently from freshwater body of different perennial pond. This present database of ichthyofauna clearly indicated that 11 fish species, 8 genera, 6 families and 1 order have lost from this investigated area. Basically, this agricultural based area associated with profuse application of various chemicals, poisons and drugs in agricultural field that largely polluteperennial water body andultimately exerting growing pressure on living aquatic resources and driven significant fish biodiversity decline. However, over fishing, chemicals, agricultural runoff and other forms of pollution are most important factors which should be restricted for the conservation of freshwater fish biodiversity. Therefore, it may be concluded that preparation of zone wise database of these information and their implementation through Government and various Non-Government Organizations would be the key tools for conservation of freshwater fish biodiversity.

Key words: Biodiversity, Fish, Freshwater, East Midnapore district of West Bengal

INTRODUCTION

India is endowed with vast freshwater
consisting 45,000 Km. of rivers, 26,334 Km. of
canals, ponds and tanks 2.36 million hectares and
2.05 million hectares of reservoirs, which present
like harbor a rich and diversified fish fauna
characterized by many rare and endemic fish
species. About 21,730 species of fishes have been
recorded in the world; of which, about 11.7% are
found in Indian waters. Out of the 2546 species
so far listed, 73 (3.32%) belong to the cold
freshwater regime, 544 (24.73%) to the warm
freshwater domain, 143 (6.50%) to the brackish
water and 1440 (65.45%) to the marine
ecosystem. The freshwaters of India have been
viewed from a single perspective: that of economic
production. They are to be sources of irrigation or
urban-industrial water supply or of hydro power;
they are to receive sewage and industrial waste;
they may produce edible fish. In this strictly utilitarian framework, there is no space to
conserve the rich heritage of freshwater
ichthyofauna diversity of the country. Due to
irrational fishing practices, environmental
aberrations like reduction in water volume,
increased sedimentation, water abstraction, and
pollution over the years this diversity is on a decline
and few species have been lost from the
freshwater ecosystem of India and some are
belonging under endemic, endangered and
threatened category. A recent series of reviews
(Dudgeon, 1999, 2000a, b, c, d, 2002a, b) has
underscored the alarming condition of the region’s
rivers, which has been apparent for over a decade
(Dudgeon, 1992). Their waters are grossly
polluted, and dams and impoundments influence
their natural discharge to such an extent that the
lower Ganges and the Indus virtually cease to flow
during the dry season (Postel and Richter, 2003).
In the present context, freshwater fish biodiversity loss is an alarming threat and its conservation is only the solution of the problem. Though, West Bengal comprises diversified ichthyofauna in various habitats but freshwater fishes are a poorly studied group. There is no proper documentation since information regarding distribution, population dynamics and threats is incomplete, and most of the information available is from a few well-studied locations only. Therefore, it is important to prepare a zone wise database for listing the fish diversity in our country. Moreover, a data base on fish biodiversity is also essential as a decision making tool for conservation and management of fish germplasm, protection and preservation of endangered species and mitigation of anthropogenic activities so as to fulfill India’s obligations under conventions on biological diversity with special reference to Articles 6 and 8 of UNEP (1992). In the present paper an attempt is made to prepare a consolidated list of freshwater fish species, to determine the cause of fish diversity loss and to suggest a various management plans relevant to the conservation of fish diversity of this perennial freshwater body.

MATERIALS & METHODS

Ten perennial ponds located in the Ramnagar,
East Midnapore (Latitude 21.8°N and Longitude
87.8°E), West Bengal, India was selected for present
survey (Fig. 1).

Freshwater fish species inhabiting the perennial ponds were collected to study the qualitative abundance. The specimens were collected using various types of fishing methods such as cast nets (16 mm, 18 mm, 22 mm), gill nets (32 mm, 38 mm, 64 mm, 78 mm, 110 mm), drag nets (4 mm, 15 x 3 meters), scoop nets and other local contrivances. Collected fish samples were preserved in 8% formalin for detailed examination and identification with the help of literature (Talwar and Jhingran, 1991; Sen, 1992; Jayaram, 1981, 1999). Extensive survey was also performed to collect the fish abundance data of previous year from 1990 to 1995 from local persons of the selected area.

Water samples were collected from ten ponds and examined for water pH and dissolved oxygen levels using specific electrode and probe of a Multiline System (F/SET-3, Best-Nr. 400327, WTW Wissenschaftlich-technische Werkstatten 82362 Weilheim, Germany), respectively. The concentration of ammonium-N, orthophosphate and hardness of water sample were analyzed following the standard methods described by APHA (1995). Water and sediment samples were collected from ten ponds and examined to identify the abundance of food (Plankton, Benthos and aquatic vegetation etc.) available for fish in the pond.

RESULTS & DISSCUSION

In the period from 1990 to 1995, the forty-four fish species under 29 genera, 18 families and 8 orders were recorded, whereas, thirty-four species from 21 genera and 12 families under 7 orders were presently collected and identified from freshwater body of different perennial pond of Ramnagar, East Midnapore. Maximum number of species (13 – 16) was found under the order Cypriniformes, whereas order Symbranchiformes comprised minimum number (1) among eight orders. The Scientific, common and local name of the species, together with their systematic position, commercial value and availability were described in Table 1a, b.

This showed that about 10 fish species were ornamental, whereas left over 35 species were food fish and both groups of fishes have potent commercial value. Of the 45 recorded fish species, 7 were belonging to exotic fish and remaining fish species were indigenous group. Among all species listed in the Table 1a, b, 5 were belonging under Indian major carp and 8 were recorded as jeol fish category.

The foods available to fishes in the ponds were populated with planktonic and benthic communities consisting of plants and animals.The phytoplanktonic communities were usually represented by major groups of algae, like green algae, blue-green algae, desmids, diatoms. Eudorino, Ulothrix, Volvox, Chlorococcum, Pediastrum, Oocystis, Tetrallantos, Sceredesmus, Coelastrum, Oedogonium, Cladophora, Spirogyra, Microcystis, Aphanothece, Merismopedia, Dactylococcopsis, Spirulina, Oscillatoria, Lynabya, Symploca, Nostoc, Aradaera and Raphidiopsis are the major knowngenera of phytoplankton. Protozoans, rotifers, cladocerans, copepods, and ostracods were represented as zooplanktonic communities found in ponds. Various animal larvae, worms and some immature stages of fishes are also found as occasional plankton. Zooplanktonic organisms like -Cyclops, Cypris, Daphnia, Diaptomus, Microcyclops, Stenocypris, Cyclestheria, Pleuretra, Anuraeossia, Brachionus, Platyias, Keratella, Euchlanis, Dipleuchlanis, Triplechilanis, Macrochaetus, Mytilina, Epiphane, Diplois, and Monostyla, Chironomids are major genera.The benthic food communities available to fish are small water insects, various worms, nematodes etc. Aquatic vContd. Table 1a, b egetation are also available to some fishes as a food like- Lemna, Pistia, Trapa, Chlorelle, Valisneria, Azolla, Anabaena, Eichonea, Najas, Hydrilla and Wolfia. The water pH ranged from 6.8 to 8.2 in ten ponds. Concentration of dissolved oxygen and hardness of water varied between 6 to 12.3 mg/L and 92 to 206 mg/L during the period of investigation, respectively. The value of ammonium-N and orthophosphate concentration ranged from 0.065 to 0.296 mg/Land 0.052 to0.130 mg/L, respectively in different ponds.Present extensive survey allowed to gather data and essentially to develop the concepts of the number of previous (from 1990 to 1995) and present fish species inhabiting the perennial freshwater body of the area. Collected data demonstrated that 45 species from 29 genera and 18 families were found fewer than 8 orders during the period from 1990 – 1995 year, whereas 34 species from 21 genera and 12 families fewer than7 orders are recorded presently (Table 1a, b). The present database of ichthyofauna clearly indicated that 11 fish species, 8 genera, 6 families and 1 order have lost from the investigated area during this period (Fig. 2). This 11 species of fish that have most possibly become locally are primarilylarge population size of fishes having high consumption value and subjected to heavyharvesting and affected by various anthropogenic activities such as: unethical over fishing, using of chemicals and poisons, dynamiting and habitat destruction of natural spawning and breeding grounds of the fishes.
Human activity is causing the extinction of animal, plant and microbial species at rates that are a thousand times greater than those which would have occurred naturally (Wilson, l988). Basically, this agricultural based study area associated with profuse application of various chemicals, poisons and drugs as fertilizer, pesticides, insecticides, herbicides and antibacterial agents in agricultural field that largely pollute perennial water body and ultimately exerting growing pressure on living aquatic resources (like: planktonic, benthic and vegetative food of fish) present in the different niches of aquatic ecosystem and driven significant biodiversity decline or loss through bioaccumulation and biomagnifications of pollutants.Despite environmental damage caused by losing the ecosystem balance, the fish yield has also been drastically decline due to losing a number of commercially important fish species from this zone. Pimbert (1993) acknowledges that most of the species important for the maintenance of ecological processes are located in human-managed ecosystems such as agricultural and forestry land.

CONCLUSION

On the whole, taking into account, fish biodiversity conservation represents another major environmental challenge at the global level, and will continue under threat if there is no strenuous policy action to curb human activity. Few important management plans have been considered from the study for the conservation of fish biodiversity in the freshwater body which should be inserted into the fishery policies of the Government, such as, identification and listing of threatened and endangered fish species of freshwater body, determination of population size and distribution, find out the breeding behavior of threatened fish species which is essential for both ex situ and in situ conservation of the species, development of techniques of captive breeding and bloodstock maintenance of fishes of potential economic importance.

Establishment of hatcheries for bloodstock maintenance to in situ conservation and aqua ranching as a substitute for their natural recruitment. However, over fishing, chemicals, agricultural runoff and other forms of pollution are most important causes of fish biodiversity loss, which should be restricted for the conservation of freshwater fish biodiversity. From this point of view, it may be concluded that the zone wise database of this information and their implementation through Government and various Non-Government Organizations would be a key tools for conservation of freshwater fish biodiversity.

REFERENCES

APHA. (19th Ed) (1995). Standard Methods for the Examination of Water and Wastewater, American Public Health Association. (Washington: DC)